Summary

In the temperate zone of the southern hemisphere and in some countries of South East Asia, high levels of influenza activity continued to be reported. In Central America and the Caribbean increased influenza activity was reported in a few countries. Influenza activity in the temperate zone of the northern hemisphere was reported at low levels. Worldwide, influenza A(H3N2) viruses are predominating.

• In temperate South America, influenza activity, severe acute respiratory infection (SARI) and influenza like illness (ILI) indicators decreased in the countries reporting data. Influenza A(H3N2) viruses predominated in the region with some B virus activity reported as well.
• In Southern Africa, seasonal activity appeared to decrease after peaking in week 26, with influenza A(H3N2) being the most detected viruses.
• In Oceania, seasonal influenza activity continued to increase, with influenza A(H3N2) and B viruses present in the region.
• In tropical South America, influenza activity remained low.
• In the Caribbean and Central American countries, respiratory virus activity remained generally low, and increased in some countries.
• In East, Southern and Western Asia, influenza activity remained low in general.
• In South East Asia, influenza activity continued to be reported, with all seasonal influenza subtypes present in the region. High influenza activity was reported from some countries.
• In Western Africa, low influenza activity was reported in C?te d’Ivoire, Ghana, and Togo, with influenza A(H3N2) and A(H1N1)pdm09 viruses co-circulating in the region. In Eastern Africa, few influenza A(H3N2) virus detections were reported.
• In Northern Africa, no influenza virus detections were reported.
• In Central Asia, there were no updated reports on virus detections or respiratory illness indicators.
• In Europe and North America, little to no influenza activity was reported.
• National Influenza Centres (NICs) and other national influenza laboratories from 78 countries, areas or territories reported data to FluNet for the time period from 10 July 2017 to 23 July 2017 (data as of 2017-08-04 04:25:11 UTC).The WHO GISRS laboratories tested more than 58087 specimens during that time period. 9972 were positive for influenza viruses, of which 9149 (91.7%) were typed as influenza A and 823 (8.3%) as influenza B. Of the sub-typed influenza A viruses, 653 (8%) were influenza A (H1N1)pdm09 and 7505 (92%) were influenza A (H3N2). Of the characterized B viruses, 173 (58.4%) belonged to the B-Yamagata lineage and 123 (41.6%) to the B-Victoria lineage.